1. Technical Field
The present invention relates generally to improved power operated shears that are useful for industrial cutting applications. In particular, the improved shears of the present invention are suitable for use in the food processing industry to cut and trim meat, and especially to cut poultry.
2. Description of the Prior Art
Hand held manually operated conventional scissors have been used for cutting and trimming meat and other food products. Conventional scissors also have been used in a variety of other industries for cutting sheet material, such as cloth, textiles or thin metals. It was necessary for an operator of the conventional scissors to use a relatively large cutting effort and often the operator""s wrist was at an unnatural orientation. Repetitive use at such orientation and large cutting effort could cause injury to the operator""s wrist. To reduce the effort needed to operate such conventional scissors, power operated shears have been devised.
Most known power operated hand held shears have various shortcomings. For example, most such shears do not have a similar physical arrangement to conventional scissors, the blade movement cannot be controlled to the same extent and in the same way as conventional manually powered shears, the blades are not easily replaced and the blades, if replaceable, are not reliably retained in the shears to withstand repeated heavy loading.
Thus, a need exists for power operated or power assisted cutting shears that are arranged, operated and controlled in a manner similar to that of conventional manually-operated scissors, and have easily replaceable blades that can withstand the repeated heavy loading that power operated shears used in a commercial setting will encounter.
The present invention is directed to replaceable blades for hand held power operated shears used in a commercial setting. The power operated shears overcome the shortcomings of the known power operated shears mentioned above and others by being closely similar in physical arrangement and operation to that of conventional manually operated scissors. Other operating advantages of the hand held power operated shears of the present invention include a controllable rate of closing of blades, a controllable extent of closing, easily replaceable blades and a reliable load bearing mounting for one of the blades.
The present invention is also directed to hand held power operated tools, and more particularly shears. While the invention will be described in connection with the preferred shears, it will be understood that other work members for accomplishing a desired task can be arranged and operated by a tool in the same or similar manner as the shear blades.
The shears include first and second blades for cutting a workpiece upon relative pivotal movement from a first open position towards a second closed position. A frame supports the blades for relative pivotal movement about an axis. A first handle and a second relatively pivotable handle are provided. One of the handles is supported for pivoting about an axis independently of the blades. The pivoting handle extends in a direction relative to the axis opposite the second blade. The other of the handles extends in a direction opposite the first blade relative to the axis. An actuator pivots the second blade relative to the first blade to impart a cutting action between blades. A servo mechanism is controlled by movement of the second blade and pivoting handle to control operation of the actuator to pivot the second blade relative to the first blade in coordination with movement of the pivoting handle.
The blades are readily replaceable. The blades are supported for relative pivotal movement. One blade is constructed to be fixed in a supporting frame. The other blade is constructed to be pivotable relative to the frame and first blade. The pivotable blade has an actuating portion extending in an opposite direction from the pivot from a cutting portion of the blade at an obtuse angle in the range of about 120xc2x0 to 170xc2x0 relative to a portion of the cutting edge.
The actuating portion of the pivotable blade has a drive slot that receives a portion of a drive link connected to a piston rod of the fluid actuator. The length and angle of the actuating portion of the pivotable blade and the distance the slot length extends, as well as the location of the pivot, are coordinated with the drive link to allow a size and arrangement of the parts that facilitate locating parts in the area of the shears that can be accommodated by the palm of the operator""s hand. The length and angle of the actuating portion at the same time produces relatively high leverage between the blade and the fluid actuator over a cutting excursion of 45 degrees of relative pivoting of the blades. The provision of relatively high leverage assures lower reaction forces at the pivot of the blades. Lower reaction forces allow lower structural weight and longer wear life. Relatively high leverage also allows the use of a relatively slim actuating cylinder that can provide adequate force using typical shop air pressures.
The pivotable blade has a heel portion forming a part of the actuating portion. The heel portion has a ride surface facing an opposed surface of the fixed blade. In one embodiment a part of the opposed surface of the fixed blade projects toward the ride surface of the pivotable blade, biasing the cutting edges of the blades into mutual contact where the cutting edges intersect.
Thus, the invention herein disclosed and claimed is, in its principal broad aspects, directed to a pair of replaceable blades for a hand-held power-operated blade-actuating device. The blades are without handles, have cooperating edges for cutting, and the pair comprises a first blade having a cutting portion and having a mounting portion by which the first blade can be fixed relative to a support and a second blade having a cutting portion and an actuating portion and constructed to be pivoted relative to the support and the first blade at a location on the second blade between the cutting portion of the second blade and the actuating portion of the second blade. A surface forms a part of the actuating portion for operatively coupling the second blade to a power actuator. The actuating portion of the second blade includes a portion that is located relative to the mounting portion of the first blade and the support structure when the blades are closed to allow attachment and removal of the blades as an assembled unit to or from the support, and is located when the blades are open to prevent the attachment or removal of the blades to or from the support. A locating surface on the pair of assembled blades extends transversely of the general extent of the blades for engaging with a surface of the support that extends transversely of the general extent of the blades when the blades are mounted on the support.
The portion of the second blade that allows or prevents attachment or removal of the blades in one preferred embodiment is constructed to underlie the mounting portion of the first blade when the blades are closed and to extend from behind the mounting portion when the blades are not closed, and when extending is obstructed by a surface of the support from moving in a direction along which the blades can be removed from the support.
In one preferred embodiment a locating surface of the assembled blades is at the pivot between the blades. In another preferred embodiment, a locating surface is provided on a mounting portion of one of the blades, and in its preferred construction, two apertures are provided, located to lie on substantially diametrically opposite sides of the pivot for the blades.
The invention, in its broad aspects applies to work members other than shears or replaceable cutting blades, but otherwise of the general description as above.
Further features of the present invention will become apparent to those skilled in the art to which the present invention relates from reading the following descriptions with reference to the accompanying drawings.